Peroxides and their Effects on Plants Essays
Figure 5: Typical injury of peroxyacetyl nitrate (PAN).A glazy bronzing on the underside of newly expanded potato leaves.
(Source from: http://www.omafra.gov.on.ca/english/crops/facts/91-015.htm)
Ethene (formerly ethylene) is a retarding phytohormone. It acts as an antagonist to the growth stimulators auxins and gibberellins as well as inducing stem thickening, fruit ripening, senescence, increased resistance and general responses to stress and wounding. Under natural conditions, the formation of ethene occurs via S-adenosyl methionine (SAM) and 1-amino-cyclopropane carboxylic acid (ACC), from which it is oxidatively released.Under acute stress situations like mechanical wounding and freezing,the origin of ethene in small amounts may be from the oxidative breakdown of stress situations mega-3 polyunsaturated fatty acids, for example, linolenic acid. Under the catalysis of copper ions, the omega-1 and -2fragment of the fatty acid derive ethene together with ethane.
Chaotic lipid peroxidation produces ethane in the absence of copper ions. Generally, ethene is determined as